长期不同管理措施下红壤剖面碳、氮储量变化特征

基于中国农业科学院国家红壤肥力长期试验平台,研究长期不同施肥、休闲和轮作措施下旱地红壤剖面(0~100 cm)土体及不同层次(20 cm/层)有机碳(SOC)和全氮(TN)储量的变化特征。结果表明,与试验初始相比,24年不施肥(CK处理)0~100 cm各层有机碳储量均有不同程度降低,但全氮储量在40~100 cm各土层表现出累积趋势。24年施化肥(N、NP、PK、NPK)和化肥配施秸秆处理(NPKS)明显增加40~100 cm有机碳和全氮储量,0~40 cm各层碳储量有所耗竭而氮储量无明显影响。24年有机无机配施(NPKM)明显增加表层0~20和40~100 cm的有机碳和全氮储量。休闲(Fallow)和轮作(NPKMR)措施大幅度提高0~100 cm各层有机碳和全氮储量,但两处理间无显著差异。对于0~100 cm整个土体而言,休闲和轮作处理大幅度增加了土壤剖面的有机碳和全氮储量,其中有机碳储量比初始分别提高64%和93%,全氮储量比初始分别提高71%和82%。不同措施下0~100 cm各层有机碳与全氮储量及其变化量间均存在显著线性相关关系(P0.01),但不同管理措施显著改变了碳氮储量间的相关关系,但储量变化量间的相互关系无统计学上的显著差异。休闲或豆科轮作措施能显著提升红壤剖面碳、氮库容,是红壤肥力恢复和培肥较优管理措施。

Variation characteristics of soil organic carbon and total nitrogen storage in red soil under various long-term managements

Based on the long-term experiment of the national red soil fertility of Chinese Academy of Agricultural Sciences, variation characteristics of changes in organic carbon (SOC) and total nitrogen (TN) storage at soil profile (100 cm) and different layers (20 cm for each layer) was studied under different managements after 24 years in upland red soil. Results showed that, compared with the initial year, SOC storage slightly decreased by the CK treatment for each layer in 0~100 cm, whereas soil TN storage increased in each layer of 40~100 cm for the CK treatment. Compared to the initial, mineral fertiliz-ers treatments ( N, NP, PK, NPK) and their combination with straw treatment ( NPKS) showed an accumulation of SOC and TN in each layer of 40~100 cm. But these treatments decreased SOC and had no effect on the TN storage in each layer of 0~40 cm. Compared with the initial level, SOC and TN storage increased obviously in 0 ~20 cm and 40 ~100 cm for the NPKM treatment. Compared with the initial, the fallow and NPKMR treatments greatly increased SOC and TN storage in each layer of 0~100 cm. But there was no significantly difference between the Fallow and NPKMR treatments. For 0~100 cm soil profile, SOC and TN storage of Fallow and the rotation with soybean treatment ( NPKMR) was the highest, for which SOC storage increased by 64% and 93%, TN storage increased by 71% and 82% compared to the initial, respectively. However, SOC and TN storage was lowest for the CK treatment. There were both a significantly linear correlations between SOC and TN, as well as the change of SOC and TN storage (P<0. 05). but there was significantly difference in the slope of the relationship between carbon and nitrogen storage ( C/N ratio of soil profile) , but no significantly difference in the slope of the relationship between the changes in SOC and TN storage at soil profile among the different management measures. Fallow or soybean rota-tion can substantially increase SOC and TN storage, and is recommended managements to restore and improve soil fertility in red soil in this area.